Each black hole has a monster appetite, consuming everything within 1,000 light years. Their “event horizon,” the region of space from which nothing can escape, is five times the size of our solar system.

“Don’t go within 1,000 light years of these holes. You’ll never get back,” says Chung-Pei Ma, a professor of astronomy at UC Berkeley who helped make the discovery.

The black holes are each 10 billion times as massive as our own Sun. Both live at the center of galaxies, just as a black hole exists at the core of our own Milky Way galaxy. “But ours is puny by comparison,” says Ma. “It’s 2,500 times smaller than these massive black holes.”

The team used the Keck and Gemini observatories, two of the largest telescopes on Earth. “We were already pushing the limits of new technology,” Ma says. “So it’s been pretty exciting to measure black holes. And we just happened to find the record breakers.”

Ma says the question is how these black holes became so big. One way is simply by eating. “If you put stuff very close to the black hole, they suck the stuff in and the black hole gains weight.”

The other method is by colliding and merging with black holes in other galaxies. “Bigger parents, bigger galaxies give birth to bigger black holes,” Ma says.

Ma says this raises the questions for scientists of whether nature or nurture plays a bigger role in the process. “Do they come from taller parents or get bigger by eating a lot of spinach?”

Finding these black holes could not only help them understand the evolution of black holes, Ma says, but also help explain how their parent galaxies form. “Galaxies are the building blocks of the universe. How do they get their size and shape? What is in the galaxy – dark matter, stars, gas? We would like to know about all of that,” she says.